Of course it may be some kind of selection bias, but my impression from seeing many startups, is that:
with good execution, bad ideas often lead to good ideas. I know more than one nontrivial business that essentially started out with a bad idea, but the execution was enough to see what was bad about it, and that there's a related idea that's good.
I've seen much fewer cases where, despite bad execution, a good idea shines through: sooner or later, usually sooner, the competition wins when the execution is bad.
with good execution, bad ideas often lead to good ideas. I know more than one nontrivial business that essentially started out with a bad idea, but the execution was enough to see what was bad about it, and that there's a related idea that's good.
I've seen much fewer cases where, despite bad execution, a good idea shines through: sooner or later, usually sooner, the competition wins when the execution is bad.